TTF-1 Expression is Correlated with Necessity of Postoperative Radiotherapy in Stage IIIA-N2 Lung Adenocarcinoma

Abstract

The role of postoperative radiotherapy (PORT) in patient with stage IIIA-N2 non-small cell lung cancer is still controversial. It is urgent to explore the prognostic factor which might be helpful to make treatment choice. Thyroid transcription factor-1 (TTF-1) is overexpressed in up to 95% of primary lung adenocarcinoma. Several studies stated that TTF-1 is a prognostic factor in NSQ-NSCLC with conflicting results by reasons of different stages and treatments. Here, we conducted this study to gain a better insight into the association between TTF-1 expression and the necessity of postoperative radiotherapy in patients with stage IIIA-N2 lung adenocarcinoma after R0 resection. Patients with pathologically confirmed inoperable stage IIIA-N2 lung adenocarcinoma and underwent R0 resection with or without PORT in our institution were eligible. Data on demographics, histology, invasion, radiotherapy, chemotherapy, and survival were collected.TTF-1 expressions were determined by immunohistochemistry using available specimen after resection. Patients were classified into the TTF-1 overexpression group (TTF-1 : 3+) and TTF-1 not overexpression group (TTF-1 score 0-2+). Overall survival(OS), progression free survival(PFS), local regional relapse free survival(LRFS) and distant metastasis free survival(DMFS) were calculated from the date of resection. The necessity of PORT is assessed by log-rank test. From October 2006 to April 2015，101 patients fulfilled the enrollment criteria. Fifty-seven patients were male and 44 patients were female. The median age was 56 years old (34-74 years old). Negative, score 1+, score 2+ and score 3+ TTF-1 expression were in 8, 8,17, 68 patients, respectively. Median follow up time was 26.8 months. In patients with TTF-1 overexpression, 19 patients received PORT and 49 did not. For these patients, none of the OS(82.9% vs.81.8%,P=0.731), PFS(57.9% vs. 51.5%P=0.518), LRFS(100% vs.97.6%P=0.513) and DMFS(63.2% VS.62.4%P=0.910) were associated with PORT .In patients without TTF-1 expression, patients who received PORT got more favorable OS (50.0% vs.20.8%P=0.137)and PFS(83.3%VS.22.0%,p=0.028) compared with who did not. Moreover, there is no significant differences in LRFS (100% VS 86.5%p=0.395) and DMFS (66.7%vs 47.1%P=0.442) between patients with and without PORT. This retrospective study demonstrates that patients with TTF-1 score 0-2+ might benefit more from postoperative radiotherapy.